AllerTop via Amazon offers the GloriSkin 20% Vitamin C Serum 1-oz. Bottle for $16.95. Coupon code "P8E36K6A" cuts that price to $11.86. With free shipping, that's $5 off and the lowest price we could find. It also contains Vitamin E oil, Hyaluronic Acid, Ferulic Acid, and Jojoba Oil.